The present invention relates to a filter apparatus comprising a housing and a filter insert arranged in the housing between an inlet opening and an outlet.
U.S. Pat. No. 5,882,367 discloses a filter apparatus in which a filter cartridge is disposed in a substantially cylindrical housing. On the lateral surface of the filter housing, an inlet opening is provided, which communicates with an annular space formed between the filter cartridge and the housing. Within the filter cartridge, a chamber is formed from which the filtered air is discharged through an outlet fitting. The outlet fitting is fixed in snap-in relation to the end face of the housing.
In this known arrangement, the connection fitting for the air outlet is inserted into an opening of the housing in snap-in relation. For this purpose, the material of the housing must, on the one hand, be sufficiently elastic to enable the temporary deflection necessary for the snap-in connection. On the other hand, the material must have sufficient rigidity to hold the connection fitting securely on the housing. These requirements can at best be satisfied by expensive synthetic resin materials, which would, however, result in very expensive filter devices and therefore do not usually come into consideration.